From: drh <drh@noemail.net>
Date: Sat, 28 Jul 2018 21:01:55 +0000 (+0000)
Subject: Add a small cost penalty to sorting to bias the query planner in favor of
X-Git-Tag: version-3.25.0~87
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f559ed3400d826c494bb23bbf31d280e7fbee28f;p=thirdparty%2Fsqlite.git

Add a small cost penalty to sorting to bias the query planner in favor of
plans that do not require a final sorting pass.

FossilOrigin-Name: 85b9beb4605eb0cfe2ed063c2a1925186c9e37031f78c875e60a347cce891638
---

diff --git a/manifest b/manifest
index 950d1a5eaa..c1b56c8869 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Do\snot\sallow\sa\scolumn\sreference\sthat\sis\sconverted\sinto\sa\sconstant\sby\sthe\nWHERE-clause\sconstant\spropagation\soptimization\sto\sbe\smoved\sto\sthe\sinit-time\nconstant\sexpression\slist,\sas\sthe\stable\sreference\swill\snot\swork\sthere.\nThis\sfixes\sa\sproblem\sfound\sby\sOSSFuzz.
-D 2018-07-28T16:24:08.475
+C Add\sa\ssmall\scost\spenalty\sto\ssorting\sto\sbias\sthe\squery\splanner\sin\sfavor\sof\nplans\sthat\sdo\snot\srequire\sa\sfinal\ssorting\spass.
+D 2018-07-28T21:01:55.748
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 0a3a6c81e6fcb969ff9106e882f0a08547014ba463cb6beca4c4efaecc924ee6
@@ -583,7 +583,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c d44a0811afd2155b1157c38b33141d4ac028fda6232485bed664015bb05819ca
 F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
 F src/walker.c ba7225773931760cf60bf22f34d0cce2588df7ce5ce0f215a52eb88234b55ac4
-F src/where.c fae13835da8cd457bbc50a8530b1f4bfe6eb173dec0687cf1572fc02a7aec415
+F src/where.c 52ab6d07a6ac6e2cb2a7da41217f0b7c13ce17a30d6a1d3459e86ac94b160e15
 F src/whereInt.h b90ef9b9707ef750eab2a7a080c48fb4900315033274689def32d0cf5a81ebe4
 F src/wherecode.c 2c552dfe50d06e0916dbd49a180e4bf0accfce6d17d46a2dfeea8f75d2b5861b
 F src/whereexpr.c dc34f0df69418dedb4619f7ad61b7d31f447971223540b957a1b836a62c0ce7b
@@ -1133,7 +1133,7 @@ F test/orderby1.test e4501f54721f804ca56922e253403ac6775f88e9f07569994ce99212b3c
 F test/orderby2.test bc11009f7cd99d96b1b11e57b199b00633eb5b04
 F test/orderby3.test 8619d06a3debdcd80a27c0fdea5c40b468854b99
 F test/orderby4.test 4d39bfbaaa3ae64d026ca2ff166353d2edca4ba4
-F test/orderby5.test 8f08a54836d21fb7c70245360751aedd1c2286fb
+F test/orderby5.test 5f4d6cb93cc2f6d3f4228354310a2ce1fbd95d5bbffcba8c6482eeb62a466407
 F test/orderby6.test 8b38138ab0972588240b3fca0985d2e400432859
 F test/orderby7.test 3d1383d52ade5b9eb3a173b3147fdd296f0202da
 F test/orderby8.test 23ef1a5d72bd3adcc2f65561c654295d1b8047bd
@@ -1597,7 +1597,7 @@ F test/walrofault.test c70cb6e308c443867701856cce92ad8288cd99488fa52afab77cca6cf
 F test/walshared.test 0befc811dcf0b287efae21612304d15576e35417
 F test/walslow.test c05c68d4dc2700a982f89133ce103a1a84cc285f
 F test/walthread.test 14b20fcfa6ae152f5d8e12f5dc8a8a724b7ef189f5d8ef1e2ceab79f2af51747
-F test/where.test 6bfcd29db193b814e5736832ffa899b4ff2969a106b718a79375063d5eb02b29
+F test/where.test 480cfc1758ac9df3f70c6a2541ff586f6a4833354d5ecb548f643e30e31fddc8
 F test/where2.test 478d2170637b9211f593120648858593bf2445a1
 F test/where3.test 2341a294e17193a6b1699ea7f192124a5286ca6acfcc3f4b06d16c931fbcda2c
 F test/where4.test 4a371bfcc607f41d233701bdec33ac2972908ba8
@@ -1753,7 +1753,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P e4b4737e348235e196a45e1b71876b82e0cc836e1c5c16ea5f9333b7509b59b8
-R 6a42221e806e5e8418ed63680c0877d8
+P d30b2a947313b146f29e2b53f0fd471409fda7938151241d3fb5863614f88999
+R f478416ffaa85b9b753e0ff20fb9a188
 U drh
-Z d943f4ee811a58f2418c55b10bc7aa62
+Z e3c69457c35c4a6b4c979e7c01232a05
diff --git a/manifest.uuid b/manifest.uuid
index ec702125fe..837bcd5dad 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d30b2a947313b146f29e2b53f0fd471409fda7938151241d3fb5863614f88999
\ No newline at end of file
+85b9beb4605eb0cfe2ed063c2a1925186c9e37031f78c875e60a347cce891638
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index b7e51f3d94..722a0062a5 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4056,7 +4056,11 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
                 pWInfo, nRowEst, nOrderBy, isOrdered
             );
           }
-          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]);
+          /* TUNING:  Add a small extra penalty (5) to sorting as an
+          ** extra encouragment to the query planner to select a plan
+          ** where the rows emerge in the correct order without any sorting
+          ** required. */
+          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]) + 5;
 
           WHERETRACE(0x002,
               ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",
diff --git a/test/orderby5.test b/test/orderby5.test
index c9cce703ba..e83116bae0 100644
--- a/test/orderby5.test
+++ b/test/orderby5.test
@@ -83,7 +83,7 @@ do_execsql_test 2.1a {
 
 do_execsql_test 2.1b {
   EXPLAIN QUERY PLAN
-  SELECT * FROM t1 WHERE likelihood(a=0, 0.05) ORDER BY a, b, c;
+  SELECT * FROM t1 WHERE likelihood(a=0, 0.03) ORDER BY a, b, c;
 } {/B-TREE/}
 
 do_execsql_test 2.2 {
diff --git a/test/where.test b/test/where.test
index 216325d03b..db0bc47a7c 100644
--- a/test/where.test
+++ b/test/where.test
@@ -582,7 +582,7 @@ do_test where-6.7.2 {
   cksort {
     SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 1
   }
-} {1 100 4 sort}
+} {1 100 4 nosort}
 ifcapable subquery {
   do_test where-6.8a {
     cksort {